text: struct pvclock_vcpu_time_info {
      u32   version;
      u32   pad0;
      u64   tsc_timestamp;
      u64   system_time;
      u32   tsc_to_system_mul;
      s8    tsc_shift;
      u8    flags;
      u8    pad[2];
  } __attribute__((__packed__));
  
  struct pvclock_wall_clock {
      u32   version;
      u32   sec;
      u32   nsec;
  } __attribute__((__packed__));
  
  u64 pvclock_now_ns(void);
  clock_timer init_tsc_deadline_timer(void);
  void init_pvclock(heap h, struct pvclock_vcpu_time_info *pvclock);
  